Spacing objects evenly around a curved surface
The first thing you want to do is to set your cursor to the middle of your hammer (represented by a cylinder in my case).



Then add your spike somewhere around it. To create several spikes around the edge, you have 2 methods:

1 - Use the cursor as a pivot point


Duplicate your object, rotate it around the Y axis by XX degrees and repeat the operation.





But this one is harder to modify as you have to delete you cube and realign them if you want to change its shape. The second option use an array modifier which is more adequate to the situation.

2-Array modifier
Same beginning with the cursor, but create an empty object that you want to leave at the cursor position.
This time, don't forget to move your object in edit mode instead of object mode so that the geomtry center point remain at the cursor location.



Add an array modifier to your object and deselect everything



Select the empty object as object offset and change the count





If nothing is shown, this is normal, just select the empty object and rotate it around the Y axis, your spikes should start moving.



In the example, I rotated it by 45° with 4 new cubes 4*45° = 180°, the last cube is rotated by 180°. Hope it helps